1M8N

Choristoneura Fumiferana (Spruce Budworm) Antifreeze Protein Isoform 501

Summary for 1M8N

• Entry DOI: 10.2210/pdb1m8n/pdb
• Related: 1L0S
• Descriptor: Antifreeze protein isoform 501 (2 entities in total)
• Functional Keywords: left-handed beta-helix, antifreeze protein
• Biological source: Choristoneura fumiferana (spruce budworm)
• Total number of polymer chains: 4
• Total formula weight: 50187.60

Authors

Leinala, E.K.,Davies, P.L.,Jia, Z. (deposition date: 2002-07-25, release date: 2002-09-18, Last modification date: 2018-01-24)

Primary citation

Leinala, E.K.,Davies, P.L.,Doucet, D.,Tyshenko, M.G.,Walker, V.K.,Jia, Z.
A beta-helical antifreeze protein isoform with increased activity: structural and functional insights
J.Biol.Chem., 277:33349-33352, 2002

PubMed Abstract: The insect spruce budworm (Choristoneura fumiferana)(Cf) produces a number of isoforms of its highly active antifreeze protein (CfAFP). Although most of the CfAFP isoforms are in the 9-kDa range, isoforms containing a 30- or 31-amino acid insertion have also been identified. Here we describe the functional and structural analysis of a selected long isoform, CfAFP-501. X-ray crystal structure determination reveals that the 31-amino acid insertion found in CfAFP-501 forms two additional loops within its highly regular beta-helical structure. This effectively extends the area of the two-dimensional Thr array and ice-binding surface of the protein. The larger isoform has 3 times the thermal hysteresis activity of the 9-kDa CfAFP-337. As well, a deletion of the 31-amino acid insertion within CfAFP-501 to form CfAFP-501-Delta-2-loop, results in a protein with reduced activity similar to the shorter CfAFP isoforms. Thus, the enhanced antifreeze activity of CfAFP-501 is directly correlated to the length of its beta-helical structure and hence the size of its ice-binding face.

PubMed: 12105229
DOI: 10.1074/jbc.M205575200

Experimental method

X-RAY DIFFRACTION (2.45 Å)